Automatic welding apparatus for weld build-up and method of achieving weld build-up

ABSTRACT

Apparatus for weld build-up on a surface of revolution consists of an elongated, rotatable assembly that supports, at one end, an electrical welding torch (10) terminating in a nozzle, the rotatable assembly introduction electrical welding current, inert gas, and welding wire to the torch, and including an electrically conductive, hollow, metal drive spindle. The drive spindle (200) applies driving motion and conducts electrical current for transmission to the torch, and the gas and welding wire pass through the spindle to the torch. Also, an electrically conductive carrier (110) is mounted in a radially adjustable, electrically continuous, offset relationship to a conductive body (140) joined to the end of a spindle, and a torch held is in electrically conductive relationship by the carrier, the electrically conductive body and carrier together defining a gas tight passage (FIG. 6A) extending from the spindle to the torch, a connection cavity being defined at a motion interface between the carrier and the body to maintain gas flow continuity therebetween over their range of offset adjustment. A method for weld build up on a surface of revolution, and a system of orbital torch components (FIGS. 7A-7H) are also described.

The application is a division of U.S. Ser. No. 120,393, filed Nov. 12,1987, now U.S. Pat. No. 4,892,990 which claims benefit under 35 USC 120of International Application No. PCT/US86/02498, filed Nov. 20, 1986,which was a continuation-in-part application of U.S. Ser. No. 945,182,filed Dec. 23, 1986, now issued as U.S. Pat. No. 4,687,899, which was afile wrapper continuation of U.S. Ser. No. 707,341, filed Mar. 1, 1985,and abandoned Dec. 23, 1986; and which was a continuation-in-partapplication of U.S. Ser. No. 815,682, filed Jan. 2, 1986, now allowed,which was a continuation-in-part application of U.S. Ser. No. 759,543,filed July 23, 1985 and abandoned Aug. 16, 1986. Application Ser. Nos.815,682 and 759,543 were both also continuation-in-part applications ofU.S. Ser. No. 707,341.

FIELD OF INVENTION

This invention relates to an automated welding apparatus for weldbuild-up and method of achieving the same. More particularly, it relatesto a fully automated portable or stationary welding apparatus, using theMIG process (Metallic consumable electrode using Inert Gas), and methodthat is adapted to achieve circular welding on the bore surface or theouter surface of metallic objects arranged in various ways even wherethere is small free radial space in the immediate vicinity of thewelding area.

DESCRIPTION OF THE PRIOR ART

One application of prior art welding apparatus is the building up of thebore outside diameter of a shaft or the inside diameter of a bore. Weldbuild up of a shaft may be necessary where, for example, the shaft hasbeen inadvertently undersized during manufacture, or the outer surfaceof the shaft must be hard surfaced for a particular application. Weldbuild up of bores may be necessary where, for example, the bore has beenworn oversize in service, the bore has been inadvertently oversizedduring manufacture, or the inner diameter of the bore must be hardsurfaced for a particular application. In either case, the manner inwhich the welding apparatus achieves such build-up is similar.Illustratively, the welding apparatus fuses a layer of metal with anelectric arc to the surface of the shaft or bore. Typically, the arc isinitiated at some point on the surface of the shaft or bore to be weldedand is moved around the circumference of the shaft or bore, depositingmetal until the starting point is reached. At this time the arc is movedto a position contiguous to the deposited weld bead and again movedaround the circumference of the shaft or bore for deposition of anotherweld bead. In this manner a layer of metal is fused to the surface ofthe shaft or bore with the axial length of the layer dictated by thenumber of weld beads deposited. One or more layers of metal can be fusedto the surface of the shaft or bore depending upon the thickness of weldbuild up required for a desired application.

With manually operated welding apparatus, the weld deposit operation issuspended at the completion of each 360° of rotation of the torch. Thisallows the operator to step-up the torch one weld deposit diameter to aposition contiguous to the completed weld bead for the next circularweld. The suspension of the weld deposit operation during step-up of thetorch head changes the operating parameters of the nozzle of the torchhead and hence can cause the physical characteristics of the welddeposit at the start of a contiguous weld circle to be of low quality incomparison to the weld deposit throughout the remainder of the weldcircle. Such low quality welds are susceptible to stress failure as allthe stress points caused by stopping and restarting cause a weak lineall the way up the workpiece.

Automatic welding apparatus for effecting weld build-up about either theexterior or the bore surface of metallic objects are well known in theart. See, for example, U.S. Pat. Nos. 4,323,750; 4,215,809; 4,237,039;4,550,235; and certain automatic welding machinery that is marketed byCecil Peck Company, of Cleveland, Ohio.

The apparatus described in U.S. Pat. No. 4,323,750 is specificallydesigned as a lining machine in which the workpiece rotates. It is madefor typically large diameter pipe that is to be lined with anothermaterial as in lining a cylinder with stainless steel for corrosionresistance. In this machine the whole welding apparatus enters the pipewhich is then rotated on rollers.

The apparatus described in U.S. Pat. No. 4,215,809 is specificallydesigned for build-up but the apparatus is a lathe and rotates theworkpiece while the welding head remains stationary, thus requiring thatthe workpiece be of limited size and configuration. For example, itwould be difficult to build up the I.D. of a crosshold in the end of along structure with this apparatus.

U.S. Pat. Nos. 4,237,039 and 4,550,235 by Fuwesi both describe portableapparatus for applying a weld bead to build up the inner surface of abore on an article that may be stationary, and then using the major partof the same apparatus to grind the surface to achieve the desireddiameter.

Regarding the apparatus of The Cecil Peck Company, generally, suchwelding apparatus consists of a module, equipped with all necessarymechanical and electrical components, that is adapted to be rotatedabout the parts to be welded. Typically a standard commerciallyavailable MIG welding unit designed for linear welding is used in suchapparatus. For radial adjustment, the entire unit, consisting of thewire feed motor, gear reduction assembly, and the wire feed rolls, alongwith the torch head, gas hose, power cables, and the wire reel, must beoffset and rotated, necessitating abundant clearances. This entire unitmust orbit the workpiece even when welding a small bore. The weldingpower source and control box are the only components of the weldingsystem that are remotely located from the weld site.

In addition to the above, U.S. Pat. No. 3,815,807 discloses a pipewelder made for joining two cylindrical objects and has no means forautomatically stepping up to form contiguous beads for building up asurface. The machine is described as effecting only one 360° weld. It isthen reversed in order to disentangle power leads, gas hose and weldingwire. It is, therefore, difficult to use as a build-up machine.

Prior art welding apparatus having mechanisms for stepping-up the torchhead after each circular weld has been finished typically includeadditional controls. These controls are provided for varying, e.g., theangular position of the torch head to the weld site or the radius of thecircle that the nozzle will travel.

It is impractical under certain conditions to do build-up using theabove described apparatus. For example, although acceptable for someapplications, devices requiring rotation of the workpiece can only beused where space is sufficient for workpiece rotation. Also, some priorart devices have proved less than satisfactory due to lack of automaticstep-up and the need for placement near the weld site of the cumbersomerequired equipment.

Also, in many circumstances, large, cumbersome items cannot be moved tothe welding machine; and the configuration of some work pieces does notallow the area to be welded to be easily reached. In these cases, handwelding must be used, even though a hand weld cannot be evenly applied,nor can one be assured of voidless weld metal, or even distribution ofheat, producing unpredictable warpage and shrinkage, and possibly cracksin the workpiece as well. In some cases, e.g., if the hole is too smallor too deep, hand welding is impossible.

Furthermore, many automatic welding apparatus are not readily portable,i.e., they are of such enormity that they are affixed to a permanentwork area. Even if they could be carried to the job site, they could notbe easily mounted in proper operative position in a quick and efficientmanner. Consequently, they are not readily adaptable for carrying outwelding operations in the field. The cost of such equipment furtherlimits their use in a repair situation or field work, instead,restricting them to production line use. In the prior art, field workhas typically been done by hand where at all possible or the equipmentdismantled, with a smaller section transported to the automatic weldingapparatus in the permanent work area, while the equipment sits idle inthe field.

SUMMARY OF THE INVENTION

According to the invention, an apparatus for weld build-up on a surfaceof revolution comprises an elongated, rotatable assembly that supports,at one end, an electrical welding torch that terminates in a nozzle, therotatable assembly being adapted to introduce electrical weldingcurrent, inert gas, and welding wire to the torch. The apparatus ischaracterized in that the assembly comprises an electrically conductive,hollow, metal drive spindle, means are provided for both applyingdriving motion to and conducting electrical current by the metal drivespindle for transmission to the torch, and the gas and welding wire passthrough the current-carrying spindle to the torch.

In preferred embodiments, the apparatus further comprises means forcontinuously rotating the spindle without axial movement, and means formoving the spindle stepwise in an axial direction at the completion ofeach circumferential pass of the nozzle over the surface to axiallyreposition the welding nozzle for depositing successive, side-by-side,circular weld beads along the surface as the nozzle rotates with thespindle; the welding apparatus is further characterized in that theconductive spindle is rotatably mounted by insulative bearings, within ahollow quill non-rotatably mounted in a manner permitting axial motion,thereby to move the spindle axially, preferably the conductive spindleis driven by a motor insulated from and mounted to move axially with thespindle; a power connector introduces welding current from a stationarysource directly to the conductive spindle at a point spaced downstreamfrom the position at which welding wire and gas are introduced into thespindle, preferably the welding wire is slidably confined within anon-insulated liner disposed within a bore of the conductive hollowspindle; the apparatus includes an electrically conductive carriermounted in a radially adjustable, electrically continuous, offsetrelationship to a conductive body joined to the end of a spindle, thetorch being held in electrically conductive relationship by the carrier,preferably the electrically conductive body and carrier defining a gastight passage extending from the spindle to the torch, a connectioncavity means being defined at a motion interface between the carrier andthe body to maintain gas flow continuity therebetween over their rangeof offset adjustment, the carrier comprising a metal block having aslidable connection interfitting with a mating connection on the bodyand a threaded connection for holding the torch, and the welding wirebeing slidably confined within a liner that extends from the hollowspindle, through the cavity means and through the passage within thecarrier, to the torch; the torch comprises an electrically conductivebody threaded in electrically conductive relationship to its support,preferably an electrically conductive torch extension supports the torchbody, the torch extension in turn being threaded in electricallyconductive relationship to its support; and the means for conductingelectrical current to the drive spindle comprises a rotatable powerconnector comprising first and second metal housings and first andsecond current conductive washers, the first housing being fixedlyattached to the spindle, the second housing being provided with anelectrical power conduit, the first washer being fixedly attached to thefirst housing, the second washer being fixedly attached to the secondhousing, and both said second washer and said second housing beingslipped over a stem of the first housing, the housings and the washersproviding the rotatable power connector with electrical powertransmission means, preferably the second washer lies contiguous to thefirst washer and is held in sliding contact to the first washer by asecuring means, preferably, the power connector further comprises a stemportion extending axially from the second housing through the firsthousing and in encircling relationship with the spindle to define afirst annular chamber between the stem portion and spindle, and slidableelectrical contact surfaces fixed to the housings and in axialengagement with each other at a location radially outward of the stemportion, the housings being axially spaced from each other between thestem portion and the electrical contact surfaces to define a secondannular chamber, preferably the rotatable power connector is made of asolid bronze, preferably the rotatable power connector is attached aboutthe rotatable drive spindle, leaving the first end of the spindle freefor entrance of welding wire and inert gas, preferably the rotatingpower connector comprises torque resisting means including an eyescrewattached to an external surface of the second housing for receiving andholding a torsional resistance bar that is attached to a stationarysurface, and preferably the securing means comprises a spring throughball thrust bearing.

According to another aspect of the invention, an apparatus for weldbuild-up on a surface of revolution comprises an elongated, rotatableassembly that supports, at one end, an electrical welding torch thatterminates in a nozzle, the rotatable assembly is adapted to introduceelectrical welding current, inert gas, and welding wire to the torch,and is characterized in that it comprises an electrically conductivecarrier mounted in a radially adjustable, electrically continuous,offset relationship to a conductive body joined to the end of a drivespindle, and a torch is held in electrically conductive relationship bythe carrier, the electrically conductive body and carrier defining a gastight passage extending from the spindle to the torch, a connectioncavity means being defined at a motion interface between the carrier andthe body to maintain gas flow continuity therebetween over their rangeof offset adjustment.

In preferred embodiments of this aspect of the invention the carriercomprises a metal block having a slidable connection interfitting with amating connection on the body and a threaded connection for holding thetorch; and welding wire is slidably confined within a liner that extendsfrom the drive spindle, through the cavity means and through the passagewithin the carrier, to the torch.

According to still another aspect of the invention a method of weldbuildup up on a surface of revolution comprises the steps of:

(a) holding the workpiece fixed against rotation;

(b) rotating an orbital welding torch in a circular path in an amountequal to about 360° around the surface to a limit point while at thesame time continuously feeding weld wire from a source of wire andelectrical power to the torch to form a substantially circular weld beadon the surface;

(c) immediately stepping the torch in an axial direction upon the torchreaching the limit point for a distance equal substantially to the widthof the circular weld bead while at the same time continuing to rotatethe torch and continuing to feed the wire and electrical power to thetorch;

(d) rotating an orbital welding torch in a circular path in an amountslightly less than 360° around the surface to a limit point while at thesame time continuously feeding weld wire and electrical power to thetorch to form a substantially circular weld bead on the surface;

(e) repeating step (c);

(f) repeating steps (d) and (c) as desired; and

(g) lastly, repeating step (b).

According to still another aspect of the invention, for use in weldbuild up of a surface of revolution, an orbital welding torch system ofa minimal number of components adapted for assembly, at a work site,into a torch of axial length and radial offset determined for thewelding job to be performed comprises a welding torch comprising, atorch body of length determined for the welding job to be performed, amale coupling connected to a first end of the torch body and adapted forcoupling the torch to a welding machine, a torch head connected to asecond end of the torch body and defining an end surface disposed at anangle to the axis of the torch body, the surface supporting a gasdiffuser and a contact tip surrounded by a welding nozzle, a conduitliner means extending through the male coupling member, the body, andthe torch head, the liner defining a conduit for passage of welding wiretherethrough to the contact tip, the male coupling member, the body andthe welding head together defining a conduit for passage of inert gasthrough the torch into the diffuser, and the male coupling member, thetorch body, torch head, diffuser, contact tip and nozzle being ofelectricity-conducting material for transmission of electrical currenttherethrough.

In preferred embodiments of the torch system the torch body comprises alength of tubing having an inner diameter sized to receive the malecoupling member and the torch head in press fit; the system furthercomprises at least one torch extension means for increasing the axialextent of an assembly including the torch, the torch extensioncomprising: an extension body of length determined for the welding jobto be performed, a male coupling member connected to a first end of theextension body and adapted for coupling to a welding machine, a femalecoupling member connected to a second end of the extension body andadapted for coupling to a male coupling member, and a conduit linermeans extending through the male coupling member, the body and thefemale coupling member, the liner defining a conduit for passage ofwelding wire therethrough, the male coupling member, the body and thefemale coupling member together defining a conduit for passage of inertgas therethrough, and further being of electricity-conductive materialfor transmission of electrical current therethrough; the torch systemfurther comprises a ball swivel connector comprising: a body memberhaving a male coupling member for connection of the connector to awelding machine, a swivel member pivotally connected to the body memberand having means for connection of a male coupling member thereto, and aconduit liner extending through the body member and the swivel member todefine a conduit for welding wire therethrough, the body member and theswivel member further defining a conduit for passage of inert gastherethrough and being formed of electricity-conducting material fortransmission of electrical current therethrough, the swivel memberadapted to be disposed with its axis at an angle to the axis of the bodymember for positioning a torch nozzle at a point offset from the axis ofa welding machine, while maintaining passage of gas, electrical currentand welding wire therethrough; preferably the system further comprisesmeans for fixedly clamping the swivel member relative to the body; andthe system further comprises means for rotational orientation of anassembly of system components relative to a welding machine comprising:rotatable means adapted for threaded engagement by a male couplingmember, and clamping means for fixing the rotatable means relative tothe welding machine.

Objectives of my invention include providing for a welding apparatus andmethod that may conveniently, accurately and cost effectively weld inneror outer circular surfaces of comparatively small or large diameters ina continuous operation, providing even, concentric welds. This is anadvantage, for instance, for build-up of worn cylindrical bearingsurfaces, both inner and outer, for the repair of broken shafts andcylinders on unwieldly equipment, or for other occasion requiring acircular, evenly applied, strong weld deposit. A further objective is toprovide a welding system that permits quick and efficient assembly, inthe field, with a torch properly sized axially and radially for aparticular job to be performed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of the bore build-up unit of the portable weldingapparatus of the present invention as it is mounted to a welding standwith magnetic base;

FIG. 2 is a side view of one embodiment of a remote wire feed device foruse with the welding apparatus of the present invention as it is mountedto a platform;

FIG. 3 is a diagrammatic view of a portion of the welding apparatus ofthe present invention;

FIG. 4 is an enlarged view of an offset adjustment means, e.g., as usedin the unit of FIG. 1, showing slots for passage of welding wire andgas;

FIG. 5a is a bottom view of the body member of the offset adjustmentmeans shown in FIG. 4;

FIG. 5b is a cross-sectional view taken along lines 5b--5b of FIG. 5a;

FIG. 5c is a side cross-sectional view of the assembled adjustment meansshown in FIG. 4;

FIG. 5d is a top view of the torch holder of the offset adjustment meansshown in FIG. 4;

FIG. 5e is a cross-sectional view taken along lines 5e--5e of FIG. 5d;

FIG. 6A is an enlarged cross-sectional view of an orbital welding torchconnected to the offset adjustment means of FIG. 3;

FIG. 6B is a side view of a further embodiment of welding torch of thepresent invention designed for large bores, and for welding outersurfaces of workpieces;

FIG. 7A is a side view partially in section of a torch assembly of theinvention, while FIG. 7B is an end view on line 7B--7B;

FIG. 7C is a side section view of another torch assembly of theinvention for small diameter bores, while FIG. 7D is an end section viewon the line 7D--7D;

FIG. 7E is a side section view of a torch extension assembly accordingto the invention, while FIG. 7F is a side view of the interengagingportions of a pair of extensions;

FIG. 7G is a side view, partially in section, of a torch orientationfitting;

FIG. 7H is a side view, partially in section, of an adjustable balljoint adapter;

FIG. 8 is an enlarged perspective cross-sectional view of the rotatablepower connector of FIG. 3;

FIG. 9 is a side view of a further embodiment of a portable weldingapparatus of the present invention with quill feeding device, rotationmotor, rotatable power connector and wire feed device, all remotelylocated from a weld site;

FIG. 9a is an enlarged cross-sectional view of a part of FIG. 9 showingthe slip-ring construction for supplying electrical power to the wirefeed device of the embodiment shown in FIG. 9;

FIG. 10 is a view of a weld layer comprising circular weld beads alongthe outer surface of a workpiece;

FIG. 11 is a view, partially broken away, of the torsionally rigidhollow flexible shaft of the present invention;

FIG. 12 is a side view, partially broken away, of the torsionally rigidshaft and casing assembly of the present invention;

FIG. 13 is a side view of another embodiment of the remote wire feedunit of the present invention;

FIG. 14 is an exploded view of the coupling of the wire feed unit ofFIG. 13 to the welding spindle of the apparatus; and

FIG. 15 is a schematic view of a welding nozzle showing the path ofmovement of the welding wire therethrough.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1, 2 and 3 show one embodiment of the welding apparatus of thepresent invention.

As shown in FIGS. 1 and 3, a bore build-up unit of the welding apparatusof the present invention comprises a rotatable spindle 200 connected atone end to a rotating means 290 via a rotatable power connector 300. Anorbital welding torch 10 is connected at the other end of the spindle200 through an offset adjustment means 100. A quill positioner 210 isalso associated with the rotatable spindle 200 for control its axialmovement.

As is shown more clearly in FIG. 3, rotatable spindle 200 consists of ametal rod with a longitudinally extending enclosed passage in the formof a axially-aligned center hole or bore 204. The rotatable spindleextends through the center of rotatable power connector 300 and quill220 of quill positioner 210, and is attached to the body of the offsetadjustment means or carrier assembly 100 by a thread connection 148(FIG. 6a). (The spindle 200 and offset adjustment means 100 may bepermanently joined, e.g., by welding or by pinning.)

The center bore of the rotatable spindle is sized to allow a piece offlexible conduit liner 240 to extend the entire length of the spindlefor communication with offset adjustment means 100, with sufficientclearance between the outside of the conduit liner 240 and the bore ofthe rotatable spindle for passage of inert gas, supplied through hose482 about the wire feed, as described below, to communicate with theorbital welding torch 10. The clearance provides the rotatable spindlewith gas transmission means.

The flexible conduit liner has a diameter large enough to receive andhold welding wire 411 and hence provides the rotatable spindle with wiretransmission means. In this regard, welding wire 411 is pushed from wirefeed device 400 by the feed rolls, 452 and 454, through a conduit liner260 of the hollow flexible shaft 480, into flexible conduit liner 240within rotatable spindle 200 and on into offset adjustment means 100 forcommunication with the orbital welding torch 10.

Inert gas enters the hose 482 surrounding the hollow flexible shaft 480through conduit 380 (FIG. 2) via a slip coupling 381 adjacent the wirefeed housing 440. The inert gas follows the passageway defined betweenthe shaft 480 and hose 482, to enter spindle 200

Electrical welding power, through conduit 390, enters the spindle 200through rotatable power connector 300.

The rotatable spindle 200 thus carries the inert gas, the electricalwelding power and the welding wire to the offset adjustment means forcommunication with the orbital welding torch.

Referring further to FIG. 3, rotating means 290 comprises sprockets 293,297, a chain 295 and a drive motor 291. Sprocket 297 is a conventionaldrive sprocket bored to fit loosely over the rotatable housing part ofpower connector 300. The space is filled with epoxy which bothelectrically isolates and secures sprocket 297 to rotatable powerconnector 300. Rotation of drive motor 291 rotates driving sprocket 293and driven sprocket 297 through chain 295. Rotation of driven sprocket297 causes the rotatable power connector to rotate, which, being securedto the rotatable spindle, as more fully described below, causes therotatable spindle to rotate in endless rotation.

As shown in FIGS. 4 and 6a, offset adjustment means 100, consisting ofbody member 140 and sliding torch holder 110, connects the orbitalwelding torch 10 to the rotatable spindle 200. The body member andsliding torch holder each have an internal cavity and openings at twoends. The cavities provide the offset adjustment means with means forcontinuous transmission of gas and welding wire in all possible radialpositions, and the body of the offset adjustment means provides meansfor electrical power transmission. The body member and torch holder ofthe offset adjustment means member are fitted to one another by adovetail 112 which allows the torch holder to slide in a radialdirection in the body member. The body member is provided with a handknob 144 connected to means (FIGS. 5b and 5d) within the body member forthis purpose. Advantageously, when orbital welding torch 10 is attachedto torch holder 110, and the rotatable spindle is attached to bodymember 140, any radial sliding motion of the torch holder to the bodymember permits the axial position of the orbital welding torch to beoffset in relation to the axial position of the rotatable spindle. Thisoffset of the torch holder to the body member determines the radius ofthe orbital welding torch and hence the radius of the circle to bewelded.

The means internal to the offset adjustment means member for moving thetorch holder relative to the body member is shown in FIGS. 5a-5e, with5a and 5b showing the body member 140 and FIGS. 5d and 5e showing thetorch holder 110. The body member is provided with a recessed dovetail142 in order to engage dovetail 112 of the torch holder when the two arefitted to one another (FIG. 5c). Within the body member is a pinion 146which mates with a rack 116 in the torch holder. Turning of a hand knob144 connected to the pinion, via a pinion shaft 146', forces thedovetail of the torch holder to slide in the recessed dovetail of thebody holder. The top of the body member also has a threaded hole 148 toengage screw threads on the bottom end of the rotatable spindle (FIG.6a). The bottom of the sliding torch holder also has a threaded hole 120to allow connection of the orbital welding torch. The torch is held inplace by an externally threaded bushing 118, pressing against a smallflange 122, shown in FIG. 6a, at the wire receiving end of the torch 10.

As shown in FIGS. 4, 5a, 5b and 5c, the body member 140 and slidingtorch holder 110 of the offset adjustment means are provided withcavities 150 and 124 respectively. These cavities provide openings orpassageways for passing the flexible conduit liner 240 from therotatable spindle through the offset adjustment means and into theorbital welding torch. These slots are milled within the central sectionof the members parallel with the dovetails. The width of the slots islarger than the diameter of the flexible conduit liner 240 in order toloosely receive this liner. In addition, these slots are sufficientlylong to permit the torch holder to move relative to the body memberwithout damaging the flexible conduit liner 240 containing welding wireas the liner snakes its way from the rotatable spindle to the torch. Theflexible liner provides the offset adjustment means with wiretransmission means. Gas also passes through these slots 124, 150, andthe sliding surfaces of the dovetail of the body member and torch holderare closely fit in order to prevent gas leakage.

Referring to FIG. 5e, a set screw 119 is provided in a threaded hole119' in the torch holder in order to secure the end of the flexibleconduit liner 240 to the holder and in communication with the end of thetorch to be connected to the threaded hole 120 of the holder. The bottomof the slot 124 is reamed at the connection of the liner 240 to permitgas to pass through the slot. Also, holes 123 are provided for passageof gas. See also FIG. 6a.

FIG. 6a shows a cross-sectional view of one embodiment of an orbitalwelding torch 10 comprising tube 16 and weld nozzle 12 attached tooffset adjustment means member 100. Drilled plugs 14 and 17 are weldedto the outer tube; plug 17, at the receiving end of the torch, ismachined to fit into the threaded hole 120 of the torch holder 110 ofthe offset adjustment means member 100. The second plug 14 is machinedto fit a diffuser 22 such as a standard MIG diffuser to hold contact tip24 within weld nozzle 12.

A flexible conduit liner 21, with a transitional fitting 18 attached toone end, is inserted through drilled plug 17 and extends through tube16. This conduit receives the welding wire 411 and provides the torchwith wire transmission means. The transitional fitting has two ducts,one of which is shown at 19, milled along two sides of the cylindricalfitting. These ducts together with the tube 16 define a longitudinallyextending enclosed passage through the torch to provide gas transmissionmeans for the torch. These ducts allow passage of inert gas from holes123 and slot 124 of the torch holder 110 of the offset adjustment meansmember 100 to the space between liner 21 and tube 16 of the orbitalwelding torch. Tube 16, defining the body of the torch, provides thetorch with electrical power transmission means.

FIG. 6b shows an extension torch for lengthening the radius which thetorch can weld. The nozzle 12 can also be pivoted inwardly to weld theoutside of a boss, shaft or the outer circumference of a metallicobject. This illustrates the versatility of the machine.

Referring to FIG. 7A et seq., a torch system for quickly assemblingcomponents into torches of different length, angle and offset, asrequired for efficiently performing a task at hand, will now bedescribed.

To permit repair welding in the field on all manner of bore diametersand depths, without requiring that there be carried to the work site inthe field a large inventory of torches of different configurations,there is provided a system of torch components.

Referring to FIG. 7A, a torch assembly 700 consists of a body 702, atorch head 704, a male coupling member 706, a flexible conduit liner708, a nozzle 710, a contact tip 712, and a gas diffuser 714. Body 702consists of drawn-over-mandrel tubing having an accurate inner diameter.Torch head 704 is machined from cylindrical bar stock with a first end716 sized for press fit within the torch body and a second end surfacemachined an angle, A, to the torch body axis, X. The angled end surfaceis drilled and tapped to receive the end of diffuser 714. Male couplingmember 706 is similarly machined from cylindrical bar stock with a firstend 718 sized for press-fit within the torch body and a second end 720externally threaded for engagement with other components of the system,described below. Referring to FIG. 7B, male coupling member 706 definesa coaxially drilled through hole 722 sized to allow the insertion of alength of flexible conduit liner 708. Surrounding this through coaxialhole are axially drilled several smaller through holes 724. Thesesmaller holes transmit inert gas to the torch body chamber 703. Tocomplete the male coupling member, at its first end, a large, 60 degreecountersink 726 is made at the through coaxial hole. The other end ofthe conduit liner 708 extends through head 704 into gas diffuser 714.Diffuser 714 is a commercially available product, typically machinedfrom brass, and may be provided with a set screw 728, although notrequired. Contact tip 712 and nozzle 710, both formed of copper, areconstructed for threaded engagement with the diffuser.

To assemble a torch 700, a piece of tubing is cut to a desired length,D, determined by the depth of the bore to be built-up, to form body 702.A torch head 704 is pressed into one end of the tubing, the angle, A, ofthe end surface, e.g., typically 45°, also being selected on the basisof the job to be performed. A length of flexible conduit liner 708 isinserted through the drilled threaded hole in the head and into the bodyuntil it exits via hole 722 in the male coupling member 706 (thefunnel-shaped counter sink 726 aiding this process). Diffuser 714 isslipped over the end of the conduit and secured by means of set screw728. The diffuser 714 is screwed into the tapped hole in the head. Atthis point, the opposite end of the flexible conduit liner will benearly flush with the end surface of the male coupling member,protruding by no more than a small amount. Contact tip 712 and nozzle710 are then screwed onto the diffuser.

In operation, inert gas under light pressure travels through the severalsmall axial holes in the male coupling member 720 and into the bodychamber 703. The inert gas is contained by the body chamber. Thediffuser 714, being exposed at its rear end to the gas under presure inthe body chamber, diffuses gas into and out the end of the gas nozzle710 which surrounds the contact tip 712 and directs gas out around thewelding arc.

Welding wire is fed into the flexible conduit liner 708 at the malecoupling end. The liner guides the wire through the body chamber andinto the diffuser and on to the contact tip.

Electrical current travels through the metallic male coupling member,body tube, head and diffuser to the contact tip.

Referring to FIGS. 7C and 7D, a small bore torch 730, sized for use inbores in the range of 7/8 inch (2.25 cms) to 21/2 inch (6.35 cms)diameter, consists of a torch body 732, a contact tip 734, a flexibleconduit liner 736, and a male coupling/torch end fitting 738. Flexibleconduit liner 736 is a short piece of spirally wound heavy wire asdescribed above. The contact tip 734 is a bent piece of copper rodmachined with a multi-diameter hole 740 axially through its center. Thehole at the wire-receiving end of the contact tip is large enough toaccept the end of the flexible conduit liner for a short depth. The holethen narrows to a loose clearance hole for the welding wire. Past thebent section of the contact tip, the hole narrows still further makingit a good fit around the welding wire to ensure smooth electrical flowand wire travel, as well as to accurately guide the wire into the weldpuddle. (The machining of the contact tip is done before it is bend toshape, and the hole at the bend is a loose clearance as otherwise thebending would pinch the hole preventing passage of the wire.) The torchbody 732 consists of a hollow, straight-sided tube which at one end ismade larger in diameter to accept internal threads (these threads may beoffset to increase the reach of the torch, as shown, or they may beconcentric). These threads fit the torch end fitting 738, describedbelow. The other end of the torch body is formed to change the angle ofthe tube to a new angle, B, to the axis of the torch body, e.g., angle Bmay be about 30°. The end of the tube is cut to an angle, e.g., of about12 degrees, from the axis of the torch body to form the nozzle end fromwhich the contact tip protrudes and welding takes place. Just before thebend to the new angle, B, in the torch body, on the back side (thenozzle side being the front), there is machined or cast a small halfround seat 742. Opposite this seat, in the wall of the tube, is athreaded hole for a set screw 744. Set screw 744, threaded into thishole, clamps contact tip 734 in place against the seat.

The torch end fitting 738 is a small piece of hex bar stock machinedwith threads on both ends. One end is machined to fit the torch bodythreads. The other end is machined to form a male coupling. The interiorof the torch end fitting is similar to the male coupling member 706,described above, having an axial hole through its center to acceptflexible conduit liner 736, and surrounding the central hole, severalsmall axial through holes to transmit inert gas to the interior of thetorch body and thus to the nozzle.

To assemble the small bore torch 730, the contact tip 734 is clamped inplace in the seat 742 provided. The conduit liner 736 is inserted intothe torch body 732 from the threaded end and slipped into the hole atthe receiving end of the contact tip. This hole holds the conduit linerin place, keeping it aligned with the contact tip so that wire travelsfrom the liner into the contact tip. Finally, the torch end fitting 738is slipped over the protruding flexible conduit liner, and the endfitting is threaded into its seat in the torch body, with the end of theconduit liner flush with or protruding by only a small distance from thesurface of the coupling.

The torches described above with reference to FIGS. 7A through 7D may beused with the orientation fitting (described below) alone, or may beemployed in conjunction with other components of the torch system.

Referring to FIG. 7E, there is shown a torch extension 750 forincreasing the axial reach of a torch to and/or into a hole. Rather thanrequiring the user to have many expensive torches of varying lengths inanticipation of future undefined jobs, the torch extensions economicallyand efficiently extend the axial reach of his torch. Torch extension 750consists of a male coupling member 752, identical to the male couplingmember 706, described above; an extension body tube 754, made from alength of drawn-over-mandrel tubing, as was the torch body 702; a femalecoupling member 756; and a flexible conduit liner 758. The femalecoupling member consists of a piece of cylindrical bar stock. A firstend is turned for a press fit into the extension body 754. An coaxialthrough hole 760 is drilled to accept a length of flexible conduitliner. The central liner hole is surrounded by several small throughaxial holes 766 to transmit inert gas. A large, 60 degree countersink764 is made into the central liner hole at the first end. (So far thefemale coupling member is identical to the male coupling member.) Thesecond end of the female coupling member is drilled and tapped 767 for amating thread to a male coupling member. A set screw 768 enters from theside of the female coupling to secure the flexible conduit liner.

To assemble a torch extension, a piece of tubing is cut to the desiredlength, D'. A male coupling member 752 is pressed into a first end ofthe extension body 754. A female coupling member 756 is pressed into thesecond end of the extension body. A length of flexible conduit liner 758is inserted through the central liner hole 770 of the male couplinguntil it is flush with the bottom of the threaded cavity 766 at thefemale coupling 756. The liner is secured by way of the set screw 768.(The flexible conduit liner can be left protruding slightly at eachend.)

Referring to FIG. 7F, the female coupling member mates with a malecoupling member of any other torch extension or the male coupling memberof a torch. The fit is such that male and female coupling membersassemble together leaving their flexible conduit liners in line with oneanother and also leaving a small gap between the end surfaces containingthe small axial holes for inert gas. This gap allows the inert gas totravel from one set of holes to the opposed set of holes whether linedup or not after torches and extensions are assembled.

Wire is fed through the flexible conduit liner at the male coupling end.The liner guides the wire through the extension body and into the femalecoupling member.

Electrical current travels through the coupling members and theextension body to the torch, which may be metal, or othercurrent-carrying material.

Referring to FIG. 7G, screw threads of the extensions and torches resultin random orientation between components. Orientation fitting 772 allowstorches and/or extensions to be secured to the torch holder 110 withproper orientation of nozzle direction with slide or other offsetOrientation fitting 772 consists of nut 774 sized for threadedengagement with the hole 120 provided in the torch holder 110, andfitting 776 having a flange 777 for engaging with the nut, and a bore778 threaded internally for receiving a male coupling, e.g., of anextension or torch. After a torch system is assembled with the fitting776, the fitting is rotated in nut 774 to the proper orientation and nut774 is tightened into holder 110 to secure the torch in the desiredpostion.

Also referring to FIG. 7H, there is shown an adjustable ball jointadapter 780. The purpose of this adapter is to increase the range andversatility of the various torches. It can be placed at any joininglocation between orientation fitting and torch. When installed, itallows the torch tip to be moved radially to increase or decrease itsrange by allowing bending or angling of the extension system so that itmay deviate from the spindle axis. This can provide rough adjustment, tobe combined with the fine adjustment accomplished by the offset headknob, or can be used alone, without offset, if desired or necessary. Thefurther from the torch the ball joint is placed, the greater thediameter range obtained, and, with this ball joint, one or two torchescould conceivably cover an entire broad range of hole sizes.

The adjustable ball joint adapter 780 consists of a ball swivel 782, aswivel body 784, and a clamping nut 786. The ball swivel 782 is turnedfrom a short cylindrical piece of bar stock. The bar stock is drilledand tapped at a first end to accept the male coupling member of anextension or torch. The second end of the bar stock is machined to aspherical shape connected to the stock by a neck of reduced diameter. Ahole 788, smaller than the diameter of the neck, is coaxially drilledpart way into the bar stock from the ball end. This hole is drilled tothe end of the neck so it will not break into the tapped hole of thefirst end. A smaller hole 789, sized to accept a length of flexibleconduit liner 790, is drilled to connect the two larger holesSurrounding this liner hole are several smaller holes 792 to pass inertgas though the member. A set screw 794 secures the flexible conduitliner by way of a threaded hole.

The swivel body 784 is machined from a short length of a larger diameterbar stock than the ball swivel. A first end is bored and a concaveradius is machined at the bottom of the bore forming a socket to acceptthe ball swivel spherical end. Threads 796 are machined in the bore upto the socket. In the bottom of this socket, a hole 797 is drilledcoaxially with the bore to a shallow depth. The diameter of this hole isabout the same as the hole through the neck section of the ball swivelmember. The other end is machined with an external thread to fit thefemale end of an extension or the orientation fitting. A hole 798 isdrilled coaxially to hold flexible conduit liner 790 and several smallerholes 799 are drilled axially around this one to transmit inert gas.

The clamping nut 786 is made from a short piece of hexagonal bar stockwith external threads machined on a first end. These threads mate withthe internal threads of the swivel body. The nut is then bored to alarge diameter and a concave radius (to match the ball swivel) ismachined at the threaded end at the edge of the bored hole.

To assemble the ball joint adapter, the ball swivel is placed into itssocket in the swivel body. The clamping nut is slipped over the shank ofthe ball swivel and threaded into the swivel body to snug the sphericalend of the ball swivel into its socket. A suitable length of flexibleconduit liner is inserted into the central hole of the swivel body untilit protrudes slightly into the tapped hole of the ball swivel. The otherend should protrude slightly from the male fitting of the swivel body.The set screw 794 in the ball swivel is tightened to secure the conduitliner.

In use, the clamping nut can be loosened and retightened each time theuser wants to bend or angle the torch, or the tension on the clampingnut can be such that the joint can be swiveled but there is sufficientfriction to hold the members in the desired position.

The ball joint seals to prevent leakage of inert gas and is metallic toconduct electrical power to the torch.

Referring now to FIG. 8, the rotatable power connector 300 provides fortransfer of electrical power to the rotatable spindle and to the weldingnozzle of the orbital welding torch at the weld site. As shown in FIG.8, the rotatable power connector comprises first and second bronzewashers, 388 and 389, respectively, a rotatable housing 370, and anotherhousing 372 preferably also made of solid bronze The first bronze washer388 is silver soldered to the rotatable housing 370. The second washeris silver soldered to housing 372 and the washer and attached housingare slipped over a stem portion 370' of rotatable housing 370 so thatthe second washer lies contiguous to the first washer.

The second washer 389 and housing 372 are held in sliding contact withthe first washer 388 and rotatable housing 370 by a spring 375 through aball thrust bearing 374. As shown in FIG. 8, metal spring 375 holdsthrust bearing 374 against housing 372 thereby forcing bronze washers388 and 389 into sliding contact insuring good electrical transfer. Asnap ring 377 maintains spring pressure. Current from a power source(not shown) is fed to the rotatable power connector via the electricalpower cable or conduit 390. Current then passes to the rotatable spindleand the orbital welding torch connected thereto. The metal constructionof the housing parts of the power connector provide the electrical powertransmission means for the rotatable power connector. Current entersrotatable power connector 300 through attachment of the cable 390 bybolt 392 to the outer surface of housing 372. This current flows throughpower connector housing 372 to bronze washer 389 and then to housing 370by way of the sliding contact with bronze washer 388. Finally, thecurrent passes to the rotatable spindle 200 to which housing 370 isfixed.

Housing 372 is prevented from rotating by torque resisting means 360consisting of eye screw 362 attached to the outer surface of the housing372 and adapted to receive and hold a torque resisting bar 361 which isnon-conductively attached to a stationary platform (FIG. 1). Any turningmovement of the housing 372 is resisted by the torque resisting bar.

By preventing housing 372 from rotating, the rotatable power connector300 allows the spindle 200 to rotate endlessly without entanglement ofthe power cable. Importantly, the configuration of the rotatable powerconnector allows the end of the spindle leading to the wire supply(lower left hand end in FIG. 8) to be left free for entrance of weldingwire on center, eliminating problems with the wire twisting.

Referring again to FIG. 3, the welding control means for axiallypositioning the weld beads is provided by the quill positioner 210consisting of a housing or quill 220, and a step-up motor 250. As shownin FIG. 3, the ends of quill 220 are provided with bearings 222 forreceiving and rotatably holding rotatable spindle 200 against relativeaxial movement. The quill forms a through cavity for holding therotatable spindle 200, allowing it to rotate about its axis inside thequill when driven by rotating means 290.

The outside surface of the quill is provided with a rack 230 fortransferring the quill and hence rotatable spindle 200 in an axialdirection. As shown in FIG. 3, rack 230 is in mesh with pinion gear 241which is secured, via shaft 241', to a worm gear 242. The worm gear inturn is in mesh with a worm 244 mounted on the shaft of step-up motor250 As shown in FIG. 1, a trip pin 245, fixed to the rotating sprocket297, trips switch 246 upon each revolution of the spindle 200 to actuatestep-up motor 250.

During operation of the welding apparatus, operation of step-up motor250 automatically moves quill 220 with rotatable spindle 200 up or downin the housing support structure 211 of the quill positioner 210. Thehousing support structure is secured to the welding stand 500, shown inFIG. 1. This motorized shifting of the quill and hence the rotatablespindle 200 repositions the orbital welding torch to a new effectiveweld depositing position as required for step-up welding.

A control panel (not shown) controls step-up motor 250 as well asrotating means 290 and wire feed motor 460. To provide step-up weldingto a metallic object according to a preferred method of the presentinvention, the step-up motor is activated after each 360° of rotation ofthe spindle 200 and torch 10 by the limit switch 246 which is tripped bythe pin 245 connected to the rotatable spindle. The distance of step-upis determined by control panel, pre-set by the operator, to switch onthe step-up motor for a specific time interval and speed Uponactivation, the step-up motor causes the rotating rotatable spindle 200in quill 220 and the attached orbital welding torch 10 to verticallyclimb by way of the rack 230 until the orbital welding torch is in aposition contiguous to the just completed weld bead During the climb ofthe rotating rotatable spindle, the control panel continues to maintainall other functions (wire feed, welding power, gas, rotation, etc.)thereby making the welding a continuous operation until the end of thewelding task.

Referring to FIGS. 2 and 3, one embodiment of a remote wire feed unit400 for use in the present invention, particularly in situationsrequiring the spindle to rotate at relatively high revolutions perminute, e.g., in buildup of bores of 3/4 inch (2 cms.) or less diameter,consists of wire reel 410, wire feed rotatable spindle 420, wire feedroll assembly 440, a torsionally rigid hollow flexible shaft 480, and amounting platform 600. Mounting platform 600 includes a base plate 602,an upright 610 and a horizontal plate 620. Horizontal plate 620 isprovided with an electrically isolated bearing block 622 for receivingand holding wire rotatable spindle 420. The wire rotatable spindle isrotatably suspended from horizontal plate 620 by bearing block 622.

The wire reel 410 is wound with welding wire electrode 411 and mountedon rotatable support bar 414, which is attached to one end of bracket415. The wire reel rotates about the axis of the support bar as wire ispayed out and fed to the welding unit. Wire feed rotatable spindle 420is fixedly attached at the one end of bracket 415. By this connection ofwire feed rotatable spindle to the wire reel, any rotation of the wirefeed rotatable spindle causes bracket 415 to orbit or rotate about theaxis of the wire feed rotatable spindle 420 and the wire 411 being fedtherethrough. This forces the wire reel to rotate perpendicularly to itsown axis and in line with the axis of the wire feed rotatable spindle.

The wire feed rotatable spindle is secured at the end opposite thebracket 415 to a wire feed roll assembly 440 which is similar to aconventional unit. The wire feed roll assembly includes a wire feedmotor 460 (a gear reduction motor) which is drivingly connected to wirefeed drive roll 452. A pressure roll 454 presses welding wire againstfeed drive roll 452. The drive roll grips the wire, draws it from thereel and pushes it into the hollow flexible shaft 480 for communicationwith the orbital welding torch.

Because wire feed rotatable spindle 420 is rotating, power must besupplied to wire feed motor 460 through slip rings 421 and 423. The sliprings are cast in epoxy along with connecting wires 421' and 423'. Theassembly is bored to fit the wire feed rotatable spindle and machined toexpose the slip rings on the outside diameter. The slip rings areconnected by way of the connecting wires 421' and 423' to the electricalleads of the wire feed motor 460. The slip ring assembly is pressed ontothe wire feed rotatable spindle 420 below the wire feed roll assembly440 in such a manner that the slip rings are in sliding contact withcarbon brushes 623 and 625 (FIG. 2) mounted on a vertical support member624 protruding from the midsection of the horizontal plate 620. Thecarbon brushes are fixedly connected to electrical wires 623', 625' thatare connected to a power control box (not shown). Power applied to thecarbon brushes passes to the slip rings and is thus applied to the wirefeed motor 460.

The rotation of the wire feed device 400 is synchronized with therotation of the orbital welding torch 10 by way of synchronizing meanssuch as the torsionally rigid hollow flexible shaft 480 extendingthrough hose 482. The shaft 480 is fixed at one end to the wire feedroll assembly 440 and is driven from the bore build-up unit by itsconnection, at its other end, to the rotatable spindle 200. As shown atthe lower left hand end of FIG. 8, this latter connection is effected bythe threaded connector 490 secured in the threaded end of the spindle200. Connection of the torsionally rigid shaft between the spindle 200and the spindle 420 causes the spindles 200 and 420 to rotate togetherat the same speed and in the same direction as measured with respect tothe path of feed of the wire passing through them. In an alternative,synchronizing means may comprise a gear train connected between the wirefeed rotatable spindle 420 and the rotatable spindle 200 of the borebuild-up unit.

As shown most clearly in FIG. 11, the torsionally rigid hollow flexibleshaft 480 includes the internal conduit liner 260. The liner iscomprised of a spirally wound cylindrical wire of metal forming anon-compressible hollow flexible structure. On the outside of this linerare placed three outer layers of spirally wound wire casings 261, 262,263. Each casing is separately comprised of four cylindrical wires woundas a set over a mandrel. The internal diameter of the first casing 261in its relaxed state is made slightly smaller than the outside diameterof the preformed conduit liner 260 by using a mandrel of appropriatesize. The first layer defined by casing 261 is assembled onto theconduit liner 260 by holding the opposite ends of the casing and turningthem in an untightening direction. This enlarges the inside diameter ofthe casing and permits insertion of the liner 260. This combinedstructure 260, 261 is then inserted into the next casing 262 bysimilarly turning the latter in an untightening direction. Casing 262 ismade with an internal diameter slightly less than the outside diameterof the assembled inner liner 260 and casing 261. This procedure is thenfollowed to insert the combined structure 260, 261, 262 into the casing263 which itself has been previously constructed with a preformedinternal diameter slightly less than the outside diameter of theassembled inner liner and casings 261 and 262.

In assembling the casings 260-263, each one is secured onto theimmediately underlying one with the lay of the wires opposite eachother. This increases the resistance of the combined structue totorsional twisting. Also, the radial tightness of each casing upon theunderlying casing holds them together. The composite casing becomes atorsionally rigid yet flexible hollow shaft which can be made in lengthslong enough to permit placement of the wire feed device at a locationremote from the weld build-up unit.

To contain the shaft during rotation, it is placed within a tubularcasing 482 shown in FIG. 12. The casing is desirable for situationswhere the shaft 480 must be long and exposed to entanglement during itsrotation, and the casing, with the shaft 480, provides a conduit forpassage of inert gas from slip coupling 381 (FIG. 2). Each end of thecasing 482 is provided with an end fitting 483, 484. The fittings areconstructed to slip over shaft end fittings 485, 486 fixed to theopposite ends of the shaft 480. The fittings 483, 484 of the casing arerotatably mounted on the shaft fittings 485, 486. The shaft endfittings, are, in turn, fixed tightly to the wire feed assembly 440 andthe spindle 200, respectively, by suitable connections, and the fittingsfurther define the conduit 487 for passage of the inert gastherethrough. Even though the casing is not secured against rotation, itdoes not rotate as the shaft 480 rotates.

Turning of the wire feed assembly as described above is necessary undercertain circumstances where it is desired to synchronize the borebuild-up unit and the wire feed unit to make them behave as if they wereon a common rotating shaft, that is, as if the wire feed unit wereinverted and placed on the end of the rotatable spindle at the powerconnector.

Wire from the wire feed unit 400 communicates with weld nozzle 12 in thefollowing manner. The wire feed roll assembly 440 draws welding wire 411from the wire reel 410 and feeds it into and through inner conduit liner260 of the torsionally rigid hollow flexible shaft 480 which directs thewelding wire into the flexible conduit liner 240 of the rotatablespindle 200 (FIG. 8). The wire then passes through the offset adjustmentmeans member 100 (FIG. 6a) through the inner conduit 21 of the orbitalwelding torch 10 and finally into communication with weld nozzle 12.

Essential to operation of the welding apparatus of the present inventionare the wire and main rotatable spindle, which retain the electricalpotential applied to them by the external power sources even when thebody of the welding apparatus is grounded. Referring again to FIG. 3, toelectrically isolate the main rotatable spindle 220 from the body of thewelding apparatus, the bearings 222 in the ends of quill 220 are ofnon-conductive material to electrically insulate the spindle from thequill. Referring to FIG. 2, to electrically isolate the wire rotatablespindle 420 from the horizontal plate 620 on the wire feed devicemounting platform, a layer of insulating material is sandwiched betweenthe outside surface of bearing block 622 and horizontal plate 620.

When considering the totally different concepts regarding the design andlocation of the components of my invention, it becomes evident that itis possible to build the described small, lightweight, completelyportable bore build-up machine, utilizing both a remotely located wirefeed assembly and remotely located control panel. Such an apparatus canbe carried to the work site by one man and attached to the work by amagnetic base or by mechanical clamping means. There are very fewrestrictions in using the apparatus of the invention due to itsextremely small size and light weight. The apparatus can be less than 18inches (about 45 cms.) tall and have virtually nonexistent requirementsfor radial clearance. Using the concept of the invention, one can easilyunderstand that there can be constructed a bore welding apparatusresembling a dentist drill, a slim basically cylindrical wand with alldrive motors, controls, and bulky components placed at another locationaway from the weld site where space, or clearance is not at such apremium. It is evident that this would be difficult with prior artapparatus. My invention makes it possible to put the necessarycumbersome apparatus at a remote site without entanglement of thevarious connecting control cables, power lines, welding wire and gashose.

The welding apparatus of the invention has been found to produce highquality weld deposits with excellent penetration. The apparatus may beused to resurface the interior of any diameter hollow structure as wellas lay a layer of weld material to the external surface of any pipe orshaft of constant or varying radius.

ALTERNATE EMBODIMENTS

It is evident that numerous alternatives of the above describedembodiments will be apparent to those skilled in the art in light of theforegoing descriptions. For example, with respect to the remote wirefeed device unit of the present invention, such alternatives may includea stationary version in which the wire feed rotation spindle is mountedintegrally to the quill positioner and spindles synchronized in rotationwith a gear train. No torsionally rigid flexible shaft would benecessary, but merely a cased flexible conduit liner to direct weldingwire into the rotatable spindle. Alternatively, where there is amplevertical clearance it would be unnecessary to have the wire feed spindleinverted. The wire feed rotatable spindle could be eliminated by placingthe wire feed roll assembly with the spool bracket 415 attached directlyon the end of the rotatable spindle.

With respect to the bore build up unit of the present invention, suchalternatives may include an apparatus as shown in FIGS. 9 and 9a whichdepicts a slender welding wand whose body is capable of slipping intosmaller, less accessible holes. In this version, the torsionally rigidhollow flexible shaft 480 is used for axial placement as well asrotational movement of the spindle 200. This allows for the placement ofa quill positioner 210 and its gear train (not shown), step-up motor250, rotatable power connector 300 with its power connection 390, gasconnection 380, drive motor 291 and wire feed device 400 to the otherend of the flexible shaft. Thus, all that is left at the weld site is arotatable spindle 200, a miniature offset adjustment means 100 andorbital welding torch 10, with the adjustment means 100 and orbitalwelding torch 10 supported, with the spindle 200, in electricallyinsulated bushings 222 within a sheath 14, the spindle 200 being axiallyslidable in and out of the sheath. Shaft 231, (replacing the quill 220of the previously described embodiment) is positioned in the quillhousing 211 and is machined with grooves 230', resembling gear teeth,around the circumference of its midsection, as shown. These grooves takethe place of the rack 230 in the original embodiment of FIG. 3. A pinion241 is fixed on shaft of step-up gear motor 250 in mesh with these teethon shaft 231. As step-up motor 250 is activated, the pinion 241 turnsmoving shaft 231 axially in housing 211.

The flexible shaft 480 is fixedly connected at its one end to shaft 231and at its other end to rotatable spindle 200. Thus, any axial movementof shaft 231 results in a corresponding axial movement of rotatablespindle 200 in its sheath 14, producing step-up of the weld nozzle.Shaft 231 has a center bore as does the rotatable spindle 200, as in thepreviously described embodiment of FIG. 3. The flexible shaft 480 alsoacts as the electrical conduit for the welding power. In addition, thespace between the flexible shaft 480 and outer casing 482 defines aconduit for passage of gas entering this space from outlet holes 231' inthe shaft 231 to the orbital welding torch.

The groove 230' in shaft 231 allow drive motor 291 to rotate shaft 231in the quill housing 211. This rotation is transferred by way of theflexible shaft 480 to the rotatable spindle and thus to the orbitalwelding torch. Electrical insulation 521 is sandwiched between housing211 and mounting bracket 530 to achieve electrical isolation of thehousing 211 to the base. Mounting bracket 530 can be of any desiredconfiguration depending upon the requirements.

Slip ring assembly 700, shown most clearly in FIG. 9a, consists of flatrings 721 and 723 which are mounted on the end of the non-conductivehousing end plate 440' of the wire feed housing 440. Copper springbrushes 721 and 723 held by housing 372 through non-conductive holder724, transfer electrical power to the wire feed motor 460.

The welding wand in FIG. 9 need not be held nor clamped in position. Itis merely slipped into the hole to be welded using bushings around itsoutside to center if necessary. Flexible shaft casing 482, being axiallyrigid, holds the wand sheath 14 in position and the rotatable spindleslips in and out of the sheath as desired for fine axial placement aswell as for step-up. The casing 482 is also torsionally rigid so itholds sheath 14 from rotating.

The construction of the welding apparatus with the wire held againstrotation is shown in FIGS. 13-15. The apparatus differs from theembodiment shown, for example in FIG. 3, in the construction of theremote wire feed device and in its connection to the back end of thewelding spindle.

As shown in FIG. 13, the wire reel 410 containing the spool of weldingwire electrode 411 is fixed to a common support 800 with the wire feedroll assembly 440'. The support is fixed relative to ground. Thisdiffers from the embodiment shown in FIG. 3 where the wire reel rotatesabout the axis of the wire relative to the wire feed roll assembly 440,and is particularly suited for use in situations where the spindle isnot required to rotate at high speeds, e.g., in buildup of bores havediameter greater than about 3/4 inch (2 cms.).

In addition, the embodiment of the invention shown in FIG. 13 mayinclude a wire straightening mechanism 802 mounted on support 800between the wire reel 410 and the wire feed roll assembly 440', or acombined wire feed and straightening system may be employed, e.g.,having feed rollers rotating about the axis of the wire, e.g., the"Roto-Drive" system of the type sold commercially by Cyclomatic of SanDiego, Calif.

The wire straightening mechanism shown in FIG. 13 is a standard designand in construction includes three rolls 803, 804, 805. The first tworolls 803 and 804 are disposed along the path of feeding of the wirebetween the supply reel and the wire feed roll assembly, with each rollbeing in engagement with the wire on one side thereof. The third roll805 is disposed between the first and second rolls on the other side ofthe wire. The third roll is laterally aligned with respect to the firstand second rolls 803, 804 to push the wire laterally of its path of feedfrom engagement with the roll 803 to its engagement with the roll 804.This operation has the effect of straightening the wire into a relaxedlinear configuration, that is, one with no tendency to coil or curve inthe relaxed state.

After passing through the wire straightening mechanism 802, the wirefeed roll assembly 440' feeds the straightened wire in the axialdirection toward the welding spindle of the apparatus. In construction,the wire feed roll assembly includes a pair of rolls 452', 454' of thesame construction as with the embodiment of FIG. 3. Due to the fact thatthe wire feed roll assembly 440' is fixed relative to the wire reel 410,the slip ring construction of FIG. 3 is no longer necessary.

The conduit between the non-rotating wire feed unit and the weldingspindle of the apparatus is a standard conduit liner encased within aprotective covering such as an air hose 807, which, with liner 806,defines a conduit for passage of inert gas introduced via gas conduit380 connected to wire feed housing 440'. A third outer casing 808 isprovided to control the bending of the wire as it is fed from the wirefeed unit to the welding unit. In this regard, it is important that thebending not be so great that it induces a permanent bend or curve backinto the straightened wire. Accordingly, the outer casing 808 isconstructed with a minimum bending radius to thus limit the amount ofbending to which the welding wire can be subjected. This minimum bendingradius is greater than that which will cause permanent bending of thewire passing therethrough.

Since the wire feed unit is not rotating the wire relative to thewelding spindle, it is necessary to provide a rotative coupling to theinput end of the welding spindle. This coupling is shown most clearly inFIG. 14. The welding spindle 200' is identical in construction to theembodiment shown in FIGS. 3 and 8, except for the fact that the endreceiving the wire from the wire feed unit is provided with a malethreaded section 809 of the welding spindle 200'. A small spindle 814 ispress fit into bearings 810, 811, held in place by snap ring 823, theinner races of the bearings seating on the surface 815 of the spindle Asection of conduit liner 806 is provided inside the small spindle 814.Also, at the input end of the small spindle, there is an opening 816sized to receive the end of fitting 819. A transitional fitting 817 isprovided in the welding spindle 200' adjacent the threaded end section809 and has a funnel-shaped opening for guiding the welding wire intothe internal conduit liner 240. This conduit liner is the same as thatshown in the embodiment in FIG. 8.

To effect the connection of the wire feed conduit assembly 806-808,coming from the wire feed unit of FIG. 12, and also provide a conduitfor passage of inert gas, a fitting 818 (FIG. 14) is provided. Thisfitting includes a first part 819 which is fixed to the end of theconduit liner 806 where it exits from the protective covering 807 bymeans of a set-screw 824. This part 819 is coupled to a threaded part820 which is adapted to thread onto the threaded back end 821 of thesmall spindle 814. This coupling places the opposed ends of the conduitliner sections in the respective components in close proximity forsmooth transition of the welding wire therethrough.

Inert gas passing within the conduit 825 between conduit liner 806 andcovering 807 passes through fitting 819 about the conduit liner andthrough ports 826 (three at 120° spacing). Coupling connection offitting 819 within opening 816 provides a small gap between the opposedend faces of the fitting and the base surface of the opening for passageof gas from ports 826 into gas passages 827 (again three at 120°, withonly one shown) in small spindle 814, without requiring alignment.Similarly, gas passes from passages 827 in spindle 814, about transitionfitting 817, which is provided with flat 828 machined along one side forthis purpose, and into the gas conduit about conduit liner 240 inspindle 200' for passage to the welding nozzle.

With the above coupling connection, the welding spindle rotates freelywith the outer races of the ball bearings 810, 811 relative to the innerraces thereof and the non-rotating wire feed unit. Further, in thisconstruction the welding wire 411 will remain fixed against rotation asit passes through the welding spindle 200' and out the end of thewelding nozzle 12' of the orbital welding torch 10'.

The internal construction of the welding nozzle is the same as with theother embodiments of the invention; and as shown in FIG. 15, engagementof the welding wire 411 with the inner wall surface 822 of the nozzlecauses it to bend. This is so because the nozzle 12' extends at an angleto the longitudinal axis of the welding spindle 200'. This engagement ofthe wire along the inner wall surface of the nozzle will place atorsional load on the section of wire before the nozzle and rotate thewire within the nozzle due to the rotational forces acting on it by therotating nozzle. This rotational or torsional force acting on the wiremay tend to cause it to twist. With the present invention, any tendencyin this respect is overcome by continuously feeding the wire at a linearspeed which is great enough to prevent any build-up of torsionalrotative forces acting on the wire, e.g, 200 inches (500 cms) perminute. In other words, the wire at any point along its length does notremain in the rotating welding nozzle long enough to permit any build-upof such torsional forces. With this construction, the wire exits fromthe welding nozzle in a constant uniform position with respect to theexit and thus with respect to the workpiece.

FIG. 10 shows a weld layer 20 comprising circular weld beads 22, 32, and42 along an outer surface of a metal tube 50 deposited in accordancewith the preferred method of the present invention. The step-up weldingof weld layer 20 begins with the orbital welding torch (not shown)depositing circular weld bead 22 and ends with the orbital welding torchdepositing circular weld bead 42 The path traversed by the orbitalwelding torch in depositing circular weld bead 22 begins at limit point26 along phantom line b--b, continues 360° back to limit point 26 and,during stepping between the limit point 26 to the phantom line c--c,continues to point 34 where circular weld bead 32 starts. In effectingweld deposit 22, the orbital welding torch is continuously rotated in acircular path from limit point 26 back to limit point 26, a rotationequal to about 360°. At the same time, electrical power and welding wireare provided The welding wire is supplied from the wire feed devicewhich is also being rotated in synchronization with the rotation of thewelding torch or held stationary with the wire instead beingstraightened into a relaxed linear configuration. After this firststepping, the torch continues rotating in a circular path in an amountslightly less than 360°, from point 34 along phantom line c--c to alimit point 36 along phantom line b--b. Subsequently, the torch isstepped in the same manner as previously described in connection withweld bead 22, to a position contiguous to weld bead 32, for depositingweld bead 42. Weld bead 42 is then deposited by a 360° rotation of theorbital welding torch from starting point 44 along phantom line c--c tolimit point 44 along phantom line c--c. In an actual welding procedure,weld bead 22 would be at the bottom of the tube 50 and weld bead 42 atthe top edge with a number of intermediate beads 32 as required.

Both the distance between each limit point along phantom line b--b ofeach weld bead and the corresponding limit point along phantom line c--cof each contiguous weld bead and the speed that the welding apparatussteps from one weld bead to a contiguous weld beads are parametersprogrammed by an operator into the control panel (not shown). With nodiscontinuities in the welding operation at the point of step-up, acontinuous weld is effected by the method of the present invention whichis of uniform high quality throughout. Consequently, the welding usingthe present invention minimizes stress failures usually incident todiscontinuous operation of a welding apparatus at the point of step-up.

Additionally, with respect to weld build-up, since step-up occurs onlyduring a specified time interval during completion of each circularweld, the circular weld deposits made by the orbiting welding head as ittraverses a metal object remains essentially perpendicular to the axisof the bore. That is, the plane in which each circular weld bead lies isperpendicular to the longitudinal axis of the cylindrical object beingworked on. If the weld bead were to travel in a helical pattern, as acontinuous gradual feed in conjunction with rotation would produce, acircumferential triangular wedge would be left unwelded at the beginningand the end of each bore being welding. This is unsatisfactory in mostcases. Neither should one return to the unwelded portion to fill in thevoid. In bore build-up welding it is desirable to complete theoperation, once started, without breaking the electric arc as eachsuccessive bead tempers the preceding bead and preheats the path to befollowed by the next weld bead helping to relieve stresses and reducehard spots, leaving a homogeneous weld surface uniform in hardness andgrain size. Having the plane of the weld bead perpendicular to the axisof the bore eliminates the unwelded wedge and the necessity of goingback to fill in the unwelded portion.

OTHER EMBODIMENTS

While the above invention has been described in conjuction with specificembodiments, it is evident that numerous alternatives, modifications andvariations will be apparent to those skilled in the art in view of theforegoing description, and other embodiments are included within theclaims.

For example, while I have described a form of my invention utilizing anoffset adjustment means, the invention contemplates a welding apparatuswhich does not include an offset adjustment means. Adjustment may beaccomplished by interchanging torches, or by use of the ball jointadapter. Also, while the foregoing description refers to step-upoperation, the apparatus contemplates effecting a helical weld beadinstead of intermittent step-up if desired by merely operating thestep-up means continuously.

It should also be apparent that step-up need not be electrical butinstead could be mechanical, such as a ratchetting means that could beoperated by revolution of the rotatable spindle stepping the torch tothe next weld circle, or such as a continuously rotating screw to form ahelical bead.

In the rotatable power connector, shown in FIG. 8, one of the washers,e.g., washer 389, may be formed of a current conductive material otherthan bronze, e.g., carbon, or a washer of carbon or othercurrent-conductive material may be disposed between washers 388, 389.

In another embodiment, the passageway through the rotatable spindle maybe sized to allow a piece of steel tubing to be inserted in the centralportion of the spindle to extend the entire length of the spindle 200from the power connector into communication with the offset adjustmentmeans 100, e.g., where the length of the spindle is too long for centerboring. In this embodiment, the major length of the spindle may beconstructed with a groove 204' extending along its surface meetingangled holes at each end of the spindle. In this embodiment, the tubeprovides the enclosed passage along the spindle, and the flexibleconduit liner 240 extends the entire length of the steel tubing, withthe clearance between the outside of the conduit liner and the inside ofthe steel tubing defining the passage for inert gas to communicate withthe orbital welding torch.

If desired, the inert gas may be introduced via the rotating powercoupling, e.g., via hose 380' shown in dashed line in FIG. 8, althoughthis is less preferred for reasons of manufacturing. Also, there is apotential for deterioration of the lubricant within the rotating powercoupling due to exposure to the flow of inert gas. Referring to FIG. 8,inert gas from conduit 380' may enter the rotatable spindle throughcrosshole 387 in the rotatable spindle shaft by entering into housing372 of rotatable power connector 300 by way of fitting 382. The gas isguided through crosshole 383 to hollow chamber 384, then throughcrosshole 385 to hollow chamber 386, and from there into crosshole 387which leads to the cavity formed between flexible conduit liner 240 andthe wall surface of the bore 204 of the rotatable spindle.

I claim:
 1. Apparatus for weld build-up on a surface of revolution,comprising:an elongated, rotatable assembly that supports, at one end,an electrical welding torch that terminates in a nozzle, said rotatableassembly being adapted to introduce electrical welding current, inertgas, and welding wire to the torch, characterized in that said assemblycomprises an electrically conductive carrier (110) mounted in a radiallyadjustable, electrically continuous, offset relationship to a conductivebody (140) joined to the end of a drive spindle (200), and a torch (10)held in electrically conductive relationship by said carrier, saidelectrically conductive body and carrier defining a gas tight passage(FIG. 6a) extending from said spindle to said torch, a connection cavitymeans being defined at a motion interface between said carrier and saidbody to maintain gas flow continuity therebetween over their range ofoffset adjustment.
 2. The welding apparatus of claim 1 wherein saidcarrier comprises a metal block having a slidable connection (112)interfitting with a mating connection (142) on said body and a threadedconnection (120) for holding said torch.
 3. The welding apparatus ofclaim 1 or 2 wherein welding wire (411) is slidably confined within aliner (240) that extends from the drive spindle, through said cavitymeans and through the passage within said carrier, to said torch.
 4. Amethod of weld buildup up on a surface of revolution comprising thesteps of:(a) holding the workpiece fixed against rotation; (b) rotatingan orbital welding torch (10) in a circular path in an amount equal toabout 360° around the surface to a limit point while at the same timecontinuously feeding weld wire (411) from a source of wire andelectrical power to the torch to form a substantially circular weld beadon the surface; (c) immediately stepping the torch in an axial directionupon the torch reaching said limit point for a distance equalsubstantially to the width of the circular weld bead while at the sametime continuing to rotate the torch and continuing to feed the wire andelectrical power to the torch; (d) rotating an orbital welding torch ina circular path in an amount slightly less than 360° around the surfaceto a limit point while at the same time continuously feeding weld wireand electrical power to the torch to form a substantially circular weldbead on the surface; (e) repeating step (c); (f) repeating step (d) and(c) as desired; and (g) lastly, repeating step (b).
 5. For use in weldbuild up of a surface of revolution, an orbital welding torch system ofa minimal number of components adapted for assembly, at a work site,into a torch of axial length and radial offset determined for thewelding job to be performed, said system comprising:a welding torch(700) comprising, a torch body (702) of length determined for thewelding job to be performed, a male coupling (706) connected to a firstend of said torch body and adapted for coupling said torch to arotatable drive spindle of a welding machine, a torch head (716)connected to a second end of said torch body and defining an end surfacedisposed at an angle to the axis of said torch body, said surfacesupporting a gas diffuser (714) and a contact tip (712) surrounded by awelding nozzle (710), a conduit liner means (708) extending through saidmale coupling member, said body, and said torch head, said linerdefining a conduit for passage of welding wire therethrough to saidcontact tip, said male coupling member, said body and said welding headtogether defining a conduit for passage of inert gas through said torchinto said diffuser, and said male coupling member, said torch body, saidtorch head, said diffuser, said contact tip and said nozzle being ofelectricity-conducting material for transmission of electrical currenttherethrough.
 6. The orbital welding torch system of claim 5 whereinsaid torch body comprises a length of tubing having an inner diametersized to receive said male coupling member and said torch head in pressfit.
 7. The orbital welding torch system of claim 5 further comprisingat least one torch extension means (750) for increasing the axial extentof an assembly including said torch, said torch extension comprising:anextension body (754) of length determined for the welding job to beperformed, a male coupling member (752) connected to a first end of saidextension body and adapted for coupling to a welding machine, a femalecoupling member (756) connected to a second end of said extension bodyand adapted for coupling to a male coupling member, and a conduit linermeans (758) 3xtending through said male coupling member, said body andsaid female coupling member, said liner defining a conduit for passageof welding wire therethrough, said male coupling member, said body andsaid female coupling member together defining a conduit for passage ofinert gas therethrough, and further being of electricity-conductivematerial for transmission of electrical current therethrough.
 8. Theorbital welding torch system of claim 5 further comprising a ball swivelconnector (780) comprising:a body member (784) having a male couplingmember for connection of said connector to a welding machine, a swivelmember (782) pivotally connected to said body member and having meansfor connection of a male coupling member thereto, and a conduit liner(790) extending through said body member and said swivel member todefine a conduit for welding wire therethrough, said body member andsaid swivel member further defining a conduit for passage of inert gastherethrough and being formed of electricity-conducting material fortransmission of electrical current therethrough, said swivel memberadapted to be disposed with its axis at an angle to the axis of saidbody member for positioning a torch nozzle at a point offset from theaxis of a welding machine, while maintaining passage of gas, electricalcurrent and welding wire therethrough.
 9. The orbital welding system ofclaim 8 further comprising means (786) for fixedly clamping said swivelmember relative to said body.
 10. The orbital welding torch system ofclaim 5 further comprising means for rotational orientation of anassembly of system components relative to a welding machinecomprising:rotatable means (776) adapted for threaded engagement by amale coupling member, and clamping means (774) for fixing said rotatablemeans relative to said welding machine.